Fibre Inflation and $\alpha$-attractors

TL;DR

This paper explores fibre inflation within string theory, connecting it to $oldsymbol{ m f extit{ ext{alpha}}}$-attractor models, analyzing higher-order corrections, multi-field dynamics, and proposing supergravity models with de Sitter vacua.

Contribution

It establishes a link between fibre inflation and $oldsymbol{ m f extit{ ext{alpha}}}$-attractors, and develops effective supergravity models with stabilized moduli and de Sitter minima.

Findings

Higher-order corrections lead to multi-field dynamics in fibre inflation.

Supergravity models can stabilize axions and produce de Sitter vacua.

The models disentangle the Hubble parameter from supersymmetry breaking.

Abstract

Fibre inflation is a specific string theory construction based on the Large Volume Scenario that produces an inflationary plateau. We outline its relation to $\alpha$-attractor models for inflation, with the cosmological sector originating from certain string theory corrections leading to $\alpha=2$ and $\alpha=1/2$. Above a certain field range, the steepening effect of higher-order corrections leads first to the breakdown of single-field slow-roll and after that to the onset of 2-field dynamics: the overall volume of the extra dimensions starts to participate in the effective dynamics. Finally, we propose effective supergravity models of fibre inflation based on an ${\overline {D3}}$ uplift term with a nilpotent superfield. Specific moduli dependent $\overline {D3}$ induced geometries lead to cosmological fibre models but have in addition a de Sitter minimum exit. These supergravity models motivated by fibre inflation are relatively simple, stabilize the axions and disentangle the Hubble parameter from supersymmetry breaking.